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Mechanical Engineering
Mechanical Engineering is a branch of engineering that encompasses the generation and application of heat and mechanical power and the design, production, and use of machines and tools. Mechanical engineering involves application of the principles of dynamics, control, thermodynamics and heat transfer, fluid mechanics, strength of materials, materials science, electronics, and mathematics.
10,989 Questions
Please use Newton's Second Law for this. F=ma, or a=F/m.
Which valve is prefered to use for ammonia tanks a globe valve or a gate valve?
If the purpose of the valve is to modulate flow, a globe valve is preferable. If the valve is only on-off, a gate valve is preferable because of lower pressure drop when the valve is open.
As wikipedia , A globe valve is a type of valve used for regulating flow in a pipeline, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body. So i think it is a globe valve to use in steam pipeline.
What is the value of specific heat of air at constant pressure?
the chemical composition of air
78% almost nitrogen 20% oxygen and other gases 1%app.among all 1% argon has comparetive higher molar mass so taking that only to get approx.result.taking 100 grm air no of mols
nitrogen 5.5 diatomic gamma 1.4
oxygen .625
argon .05 mono atmic gamma 1.66
getting the ans by
(total mols of air-1)/x =summation (moles of gas y-1)/gomma of that gas
gas y is nitrogen oxygen & argon
specific heat at cnst pressure =gamma.8.314)/gamma -1
ans 15.35 j/mol
Is Bernoulli equation applicable for unsteady flow?
The equation assumes steady state or laminar flow and hence cannot be used for turbulent flows.
Difference between Thermal relief valve and safety valve?
A thermal relief valve is a liquid-only relief due to expansion of a liquid with increased temperature.
A safety valve relieves pressure due to a gas.
It should be noted that "safety valve" is a general term which could refer to Pressure Relief Valves (PRVs) or Pressure Safety Valves (PSVs), terms which are used synonymously in some industries (such as the petroleum industry) to refer to all relief devices in general.
How can the efficiency of a Carnot Engine be increased?
Increase source temperature or decrease sink temperature.More efficient way is to decrease sink temperature.
Where to use reduced bore and full bore?
Use full bore for applications where pressure drop should be minimum (such as in the suction pipe of a pump with required NPSH very close to available NPSH), or for pipes which could be cleaned with a pig (so that the pig doesn't get stuck on the valve). In other applications a reduced bore should be OK.
How thick is 18 gauge steel tubing?
I believe it's typically rounded to .049" thick wall. Vendor sites like centralsteel.com are a good resource.
What is the origin of a cockpit in aircraft?
A cockpit is the area, usually near the front of an aircraft, from which a pilot controls the aircraft. Most modern cockpits are enclosed, except on some small aircraft, and cockpits on large airliners are also physically separated from the cabin.
Cockpit as a term for the pilot's compartment in an aircraft first appeared in 1914. From about 1935 cockpit also came to be used informally to refer to the driver's seat of a car, especially a high performance one, and this is official terminology in Formula One. The term is most likely related to the sailing term for the coxswain's station in a Royal Navy ship, and later the location of the ship's rudder controls.
http://en.wikipedia.org/wiki/Cockpit_(aviation)
Also, consider the slang meaning in English of "cock", in context of holding a control stick in an aircraft that is located between ones legs.
A number of gears grouped into a single unit is called 'gear train'.If two gear's in mesh eg, a drive gear and a driven gear also constitute a gear train which are called simple gear train and in the simplest form.simple gear train may have more than two gear's.compound,epicyclic,reverted are some other types of gear train's.
What happens if the percentage of carbon used to make steel is increased?
Steels with higher carbon content display higher strength and hardness values. Carbon, in the form of carbides, prevents slips and dislocations through dispersion strengthening. Consequently, increasing carbon also tends to decrease melting temperature as the iron content is decreased. As evidenced by the phase diagram, iron (Fe) has a higher melting temperature than carbide (Fe3C) [you can look up an Fe-Fe3C phase diagram for reference].
Dispersion strengthening: Small particles (or carbides, in this case) located on grain boundaries and inside grains effectively block dislocation movement and grain boundary sliding. Dispersion-hardened alloys typically display rapid strain hardening and good creep resistance.
What are the advantages and disadvantages of a modular plc's?
Advantages
Publicly traded companies are able to raise funds and capital through the sale of its securities. This is the reason publicly traded corporations are important: prior to their existence, it was very difficult to obtain large amounts of capital for private enterprises.
The financial media and city analysts will be able to access additional information about the business.[clarification needed]
DisadvantagesPrivately held companies have several advantages over publicly traded companies. A privately held company has no requirement to publicly disclose much, if any financial information; such information could be useful to competitors. For example, publicly traded companies in the United States are required by the SEC to submit an annual Form 10-K containing a comprehensive detail of a company's performance. Privately held companies do not file form 10-Ks; they leak less information to competitors, and they tend to be under less pressure to meet quarterly projections for sales and profits.Publicly traded companies are also required to spend more for certified public accountants and other bureaucratic paperwork required of all publicly traded companies under government regulations. For example, the Sarbanes-Oxley Act in the United States does not apply to privately held companies. The money and income of the owners remains relatively unknown by the public
What kind of product vertical milling machine produce?
milling machines carve and drill into raw products to create shapes and nearly finished products. it can produce complicated shapes, it can produce products in it cut in the flat surfaces, grooves, shoulders, inclined surfaces, dovetails, and T-slots. Various form-tooth cutters are used for cutting concave forms and convex grooves, for rounding corners, and for cutting gear teeth
What are some different thermoplastic plastics?
These are plastics which are softening while temperature increases.
Such property makes forming of end products easy.
Examples are:
Polyethylene, Polypropylene, Polystyrene, Polytetrafluoroethylene also known as Teflon, Polyvinyl chloride (PCV) to name few popular.
A grade 8.8 fastener can be manufactured from any material whose mechanical properties meet or exceed the requirements set forth in the relevant harmonised standards.
The two-digit nomenclature is not used to describe individual steel grades and only applies to metric fasteners defined under ISO 965 (as well as derived standards)
The designation system is based on two numbers e.g 8.8 . The first number is the tensile strength of the bolt material (N/mm2 )/100. The second number is = 1/100.(the ratio of the Proof (or Yield ) stress and the Tensile strength expressed as a percentage = 100.[Yield (Proof stress) /Tensile strength] /100
meaning that a grade 8.8 bolt has a nominal ultimate tensile strength (UTS) of 800N/mm2 (or Mpa) and a nominal yield strength of 640N/mm2 (or Mpa).
These values are not expressed in Kg/mm2 or PSI as the first is an expression of mass by surface-area, the second is an expression of weight by surface-area and neither are true units under the SI system.
Lastly, the actual steel grade used by manufacturers may vary but in most cases, a grade 8.8 fastener (self-colour, black-oxide or zinc plated) will be manufactured from a medium-alloy medium carbon steel, typically with 0.30 - 0.50 % Carbon and alloyed with other elements such as Molybdenum, Vanadium, Manganese and sometimes Boron or Cobalt in small quantities. These alloying elements provide the required mechanical properties to reach the minimum strength set forth by the harmonised standards.
Bare in mind that people sometimes refer to "high-tensile bolts" which are typically grade 8.8 or superior under the metric fastener system. Grade 8.8 and superior bolts should always have their grade permanently marked on the head to differentiate them from "low-tensile bolts" as inadvertantly replacing the former with the latter could have disastrous effects.
Grade 4.6 bolts are typically refered to as "low tensile" and are often used in the construction industry as these bolts offer higher ductility and resilience compared to "high-tensile" bolts.
Hope this helps.
md means polymer orientation in machine direction & td means the same in transverse direction.
What is the difference in blank and blind flanges?
Blind flange is put at the end of pipe or at the junction that would possibly be a future expansion into that direction.
Piping is easier to drill or weld at the construction stage. Once it was in use, drilling or welding will need prolong cleaning especially when the fluid transferred is combustible. For the mean of future extension, either the blind or valve would be used to seal the end.
How do you perform grinding operation on lathe machine?
The main operation in a lathe machine is to turn material. In all lathes, a piece is held and rotated around an axis while metal is cut.
What is axial force stress on materials?
In physics:
Axial Stress: A tension or compression stress created in a structural member by the application of a lengthwise axial load.
Definition Copyright ©1989 CRC Press LLC. All rights reserved.
Examples of tensile axial stress include a chain carrying a load and tension cables on a bridge. Examples of compressive axial stress include decorative columns in architecture and the steel structure of a high rise building.
How does a wheel and axel make work easier?
It allows us to move objects with the minimal amount of friction.
Would you rather drag an object or pull it on a cart?
When you have wheels underneath the object your are transporting, there are only a few points touching the ground (the wheels). Therefore, there is less friction created when you pull the object. When there is less friction, there is higher efficiency.
There are, of course, other ways it makes life easier, but that is one of the main ideas.
Hope that helped. ;)
i agree with the above answer but i would not say a wheel and axle is the main point of simple machines and their efficiency
any factor which produce motion in a body or tends to move the body..
Not only move the body but also make it change its direction or even its geometry. For instance, if you trip while running, you'll fall, and so your direction will be changed. If you press too hard, you'll smash an egg, so you've just altered the egg's geometry. These are two basic examples.
How long does it take to build a ship?
It depends upon the type of ships. there are ships which are being used and are been used even now for more than 35 years. how ever petrochemical vessels have a lifetime of 12 years,ie all dangerous cargo has 12 years,Air craft carrier has 35 years etc.. jd eby
